Field of the Invention
The present invention relates to optical apparatuses such as digital cameras and interchangeable lenses.
Description of the Related Art
Optical apparatuses used for image capturing each use a shiftable element, such as an optical element included in an optical system or an image sensor, for optical image stabilization that shifts the shiftable element with respect to an optical axis to reduce a blur of an optical image formed on an imaging plane of the image sensor due to shaking of the optical apparatus (such as camera shaking). Such optical apparatuses are required to be capable of shifting the shiftable element by a large shift amount so as to be able to reduce a large image blur due to a large camera shaking.
Japanese Patent Laid-Open No. 2000-019577 discloses an optical apparatus using a voice coil motor (VCM) as an actuator and providing a specific relation between widths of a coil and a magnet in a coil driving direction so as to be capable of shifting a shiftable element with a large shift amount.
In the optical apparatus disclosed in Japanese Patent Laid-Open No. 2000-019577, when viewed from an optical axis direction where an optical axis extends, a center of the coil and a center of the magnet overlap each other, and a movement of the coil with respect to the center of the magnet drives the shiftable element in its shift direction. In this case, when viewed from the optical axis direction, a thrust force in a shift direction becomes 0 when the center of the coil is located near a position at which a magnetic flux density of the magnet becomes its maximum. Therefore, in order to increase a shiftable range of the shiftable element, it is necessary to increase the widths of the magnet and coil.
However, an increase in the widths of the magnet and coils increases a diameter of the apparatus excessively with respect to an increase amount of the shiftable amount, thereby increasing a size of the apparatus.